免疫不育疫苗的研究进展

免疫不育疫苗主要以哺乳动物的精子或卵子蛋白以及在受精和胚胎早期发育过程中发挥重要作用的激素为靶抗原。以激素为抗原的不育疫苗产生的不育效果多为不可逆的,且对机体损伤较大。以精子表面抗原制备的疫苗能够诱导产生精子抗体和不育效果,目前已成为避孕研究的一个热点。哺乳动物卵透明带（zona pellucida,ZP）是覆盖于卵母细胞及着床前受精卵外的一层基质,其在调节精卵特异性结合、诱导获能精子发生顶体反应和阻止多精受精等方面发挥着重要作用。ZP相对分子质量较小且免疫原性强,是免疫不育疫苗理想的靶抗原,抗ZP抗体可阻断精卵结合,故可被用作人类避孕和免疫不育控制有害动物种群数量的靶抗原,但人用ZP疫苗免疫机体后造成的卵巢功能损伤和免疫抑制等问题尚有待明确。     

犬卵透明带3 DNA疫苗在小鼠模型中的避孕效果评价

为了评价犬卵透明带3(CZP3)DNA疫苗的避孕效果,采用6只雌性小鼠Mus musculus肌肉注射50μg pcDNA3-CZP3质粒后30 V电压刺激6次的方法建立实验组,以6只同等注射pcDNA3质粒的雌性小鼠为阴性对照组;初免后每周采血并用ELISA方法检测小鼠的CZP3抗体水平及第6周抗体滴度;第6周与雄鼠合笼,计算产仔数;第24周收集卵巢制成HE染色切片进行观察;最后用小鼠血清进行小鼠及犬卵透明带的间接免疫荧光实验。结果显示,1)实验组小鼠从初免第2周就产生了抗CZP3的抗体,并且与阴性对照组之间的差异有统计学意义(P<0.05);第24周实验组的抗体水平与阴性对照组之间的差异有高度统计学意义(P<0.01)。2)第6周血清中的抗体1∶4 000倍稀释时,实验组与阴性对照组之间的差异有高度统计学意义(P<0.01)。3)小鼠生育率由阴性对照组的100%降低至实验组的50%,平均产仔数由阴性对照组的(6.667±0.422)只降至实验组的(2.500±1.455)只,且实验组的抗体水平与产仔数呈高度负相关。4)卵巢HE染色切片结果显示,CZP3 DNA疫苗...     

Feral Horse Population Model and Body Condition: Useful Management Tools in Tornquist Park,Argentina?

Feral invasive mammals challenge management strategies worldwide including the feral horse (Equus caballus) population in Tornquist Park, Argentina. In this study, I constructed population matrix models using demography data collected between 1995 and 2002. I validated the models with independent counts from 2008 to 2016. I individually identified feral horses and recorded them as I walked a fixed path that covered 20 km². I performed an elasticity analysis to estimate the influence of the demographic parameters on population growth rate. In addition, I explored whether body condition score could be a proxy for carrying capacity. Model projections with the highest values of fecundity and survival exhibited by females of all ages during 1995–2002 fit the counts from 2008 to 2016, when growth rate was moderate (λ = 1.10), very well. Elasticity of adult female survival (0.54) was 4 times higher than for fecundity and survival of all other ages. Body condition of adult females at the end of winter, 2012–2013, after reductions in density, was improved compared with 2001–2002 when the population approached carrying capacity. The validated population model together with body condition score could allow managers to take more informed decisions when planning the control of feral horses in Tornquist Park. This approach could also be applied to other small, closed, feral horse populations and other large-mammal populations. © 2020 The Wildlife Society.     

Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus

The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discuss the factors that may have led to the differences in mtDNA and Y-chromosomal observations.     

SNP identification and polymorphism analysis in exon 2 of the horse myostatin gene

The myostatin gene (MSTN) belongs to the TGF-β superfamily of secreted growth and differentiation factors and is responsible for embryonic and adult skeletal muscle development. In this study, exon 2 of the MSTN gene, which encodes part of the TGF-β pro-peptide, was sequenced in 332 horses of 20 different breeds and compared with the horse MSTN gene sequence deposited in GenBank. The sequences obtained revealed the presence of 11 haplotypes represented by 10 variable nucleotide mutations, eight of them corresponding to amino acid sequence changes. This gene shows a high variability when compared with other genes. This might be an indication that some breeds have the same ancestry but different pressures of selection.     

Ultrastructural studies of the porcine zona pellucida during the solubilization process by Li-3,5-diiodosalicylate

Isolated porcine zonae pellucidae were investigated using transmission electron microscopy. It was found that the fine structure of the zona is not homogenous. The region near the oocyte consists of a more tightly packed micellar structure than the structure near the external surface. However, no clear boundary between the two structural features could be detected. The assumption that the molecular structure of the external and internal surface of the zona is not the same is substantiated by the finding that antibodies against the whole zona structure react apparently only with the more loosely bound structure on the external surface. This effect is attributed to differences in the spacial arrangements of the micellar structures rather than to differences in chemical composition. Solubilization of the zona results in a reorientation of the otherwise randomly interconnected structure. At lower Li-3,5-diiodosalicylate concentration (0.05 M) the fibrils seems to expand so that the individual fibers lie almost parallel to each other. At a higher Li-3,5-diiodosalicylate concentration (0.2 M) the individual micelles begin to break up from the zona surface, while at a still higher concentration (0.3 M) the rigid structure of the zona is completely solubilized. In the latter case no residual material could be detected in the sediment following high speed centrifugation of the mixture. These electron microscopic results correlated with the protein concentrations in the supernatant indicating that the maximal protein content (35 ng/zona) is obtained at 0.3 M or higher Li-3,5-diiodosalicylate concentrations.     

Birth sex ratios relate to mare condition at conception in Kaimanawa horses

Several hypotheses have been proposed to explain variation inbirth sex ratios, based on the premise that variation is expectedwhen the profitability of raising sons and daughters variesbetween individual parents. We tested the Trivers-Willard hypothesisthat mothers in better condition produce relatively more sonsand that mothers in poorer condition produce relatively more daughterswhen male reproductive success is more variable. We examinedbirth sex ratios in relation to mare body condition at conceptionin horses in which male reproductive success is differentiallyhelped by slight advantages in condition. Horses meet the assumptionsof the Trivers-Willard hypothesis better than many species onwhich it has been tested and in which sex ratio biases are notconfounded by sexual size dimorphism such that one sex is more likelyto die in utero in females in poor condition. Mares that hada female foal were in poorer condition at conception than thosethat had a male foal, and mares that had foals of differentsexes in different years were in significantly poorer conditionwhen they conceived their female foal. There was no relationshipbetween offspring sex and mid-gestation condition, and therewas no difference in foaling rates in relation to body conditionat conception. Consequently, sex ratio deviations are not explainedby fetal loss in utero. Furthermore, differential fetal lossof the less viable sex cannot explain the greater proportionof males produced by mares in better condition. Therefore, ourresults suggest that sex ratio modification occurs at conceptionin wild horses.